Question

Question 8 (1 point)

These brewers discovered that the smaller number of cells without oxygen used up almost as much sugar as the much larger number of cells with oxygen. Why was that?

Question 8 options:

A	More cells in mixture A used more sugar
B	Anaerobic respiration is less energetically efficient
C	Fewer cells in mixture B used less sugar
D	One glycolysis reaction uses more sugar than fermentation

Answer 1

8. B. Anaerobic respiration is less energetically efficient. In anaerobic respiration anaerobes don't use molecular oxygen as terminal electron acceptor, they use other substarte like nitrate (NO3−), fumarate, sulphate (SO42−), or sulphur (S). In aerobic organisms undergoing respiration, electrons are shuttled to an electron transport chain, and the final electron acceptor is oxygen. Oxygen is very good electron acceptor because it is a strong oxidizing agent. Nitrate (NO3−), fumarate, sulphate (SO42−), or sulphur (S) is weaker oxidizing agent in comparison to oxygen and reduction potential of these substances is less than oxygen, therefore less energy is released per oxidized molecule during anaerobic respiration. Therefore, anaerobic respiration is less efficient than aerobic. This is the reason behind smaller number of cells without oxygen used up almost as much sugar as the much larger number of cells with oxygen.